In a silver halide color photographic material, there is now most widely used the system in which the reaction of dye-forming couplers coloring to yellow, magenta and cyan with color developing agents is utilized to form a color image.
In recent years, research has been conducted for improving dye-forming couplers to be used in the silver halide color photographic material from the viewpoint of providing improvements in color reproduction and image fastness, but it can not be said that such couplers have sufficiently been improved. In particular, with respect to a cyan coupler, a phenol series or naphthol series coupler has so far consistently been used, but the dyes formed from these couplers have undesired absorptions in the blue and green regions, which has become a large obstacle against the improvement in color reproduction. Further, the small molecular extinction coefficient of a formed cyan dye is also disadvantageous to improvement in the sharpness of an image.
Recently, research has been conducted on cyan dye-forming couplers containing a new skeleton having a nitrogen-containing heterocyclic group, and various heterocyclic compounds have been proposed. There are disclosed, for example, the diphenylimidazole series couplers described in U.S. Pat. No. 4,818,672, the pyrazoloazole series couplers described in JP-A-63-199352 (the term "JP-A" as used herein means an unexamined Japanese patent application), U.S. Pat. Nos. 4,916,051 and 4,873,183, JP-A-l-105250, and JP-A-1-105251, and the condensed imidazole series couplers described in DE 4,016,418A1. In any of these couplers, improvement in color reproduction is described and they are characterized by excellent absorption characteristics of a formed dye.
However, the dyes obtained from the above couplers have the defects that the absorptions thereof are shifted to a shorter wavelength, and that fastness to light and heat is inferior, and further have a serious problem in practical use because the coupling activity of the coupler itself is small.